Last night I was merrily brush hogging along, when suddenly the tractor began running poorly and missing. Since it has only about 30 hours on it since a total rebuilt, I was a bit upset! I thought at first it was out of fuel, but it wasn't. I limped back to the shop and did all sorts of useless things, like adjusting the valves (they were fine), adjusting the carb (it was fine) and checking points gap, etc. Still missed. Then I got it running, and missing, and pulled each plug wire to see which cylinder was missing. It was #2. Then came the weird part: as I moved the plug wire back to the plug, as soon as it was close enough for the spark to jump the gap to the plug, it would run perfectly, until the wire was completely on the plug, then it would miss again! I could hold the wire about 1/4" from the plug and it would run and accelerate perfectly. With the wire on the plug, it would miss and stumble. I swapped wires between #1 and #2, and the problem stayed with #2. But when I swapped plugs, the problem moved to #1. Obviously a bad plug. I put a different plug in and it now runs fine again! All I can figure is that the spark at full strength was finding some path other than the electrodes in the plug; but when the spark was attenuated a bit the spark could not span the short in the plug, so it went to electrodes. Does that sound right?????
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